1. Field of the Invention
The invention relates to a rapidly unlockable connecting device for provisionally connecting two objects, whilst bringing about the minimum disturbance of the attitude and relative velocity of said two objects at the time of their separation.
A preferred use of such a device is in the launching and placing in orbit of space objects such as satellites, probes, etc., from a spacecraft such as a launcher, a deep-space probe, etc.
2. Brief Description of Related Prior Art
Existing unlockable connecting devices generally comprise a connecting member by which the two objects are normally connected to one another, unlocking means permitting the separation of the connecting member into two sections connected to each of the objects and initiating means able to actuate the unlocking means. The implementation of generally pyrotechnic, initiating means actuates the unlocking means, which has the effect of separating the connecting member into two sections.
In a first family of devices, more particularly illustrated by FR-A-2 661 466 and U.S. Pat. No. 3,196,745, the unlocking means comprises a segmented nut, normally kept engaged on threaded parts of each of the two sections of the connecting member, e.g. by a locking ring normally surrounding said nut. The effect of the actuation of the initiating means is to axially displace the ring with respect to the segmented nut, which is consequently then separated from the two sections of the connecting member, so that the two objects are no longer interconnected.
In a second family of unlockable connecting devices, the separation of the connecting member into two sections is ensured by the breaking of a fragile part of said member.
In each of these two families, the existing unlockable connecting devices are generally associated with ejection means, which apply between the objects an ejection force making it possible to move them apart when separation takes place. These ejection means are generally incorporated into the connecting device and in certain cases can also be outside said device.
No matter whether separation takes place by the opening of a segmented nut or by the breaking of a fragile part, the existing unlockable connecting devices are generally designed in such a way that the ejection energy, i.e. the energy for bringing to a relative velocity the objects in question, is supplied by initiating means in the same way as the energy used for separating the objects. In other words, the bringing to the relative velocity of the objects is ensured by the excess energy released by the initiating means during their operation and not used for the separation.
The particular consequence of this feature is that the ejection velocity is directly dependent on the force necessary for the separation of the objects. Therefore the ejection velocity can vary significantly, particularly when the separation of the objects takes place through the breaking of a fragile part.
Moreover, in the case where the separation is ensured by the breaking of a fragile part, it may be necessary to give said part a large cross-section, in order to enable it to withstand the loads applied thereto during launch. The energy necessary for breaking said fragile part can therefore be very high compared with the energy required for ejection, particularly when a low ejection velocity is desired.
Bearing in mind the conventionally used technologies, the combination of these two aspects makes the ejection velocity generally of a very random nature. In addition, the direct use of initiating means, usually of a pyrotechnic nature, for ensuring ejection, makes the direction of the ejection arbitrary.
Finally, the existing unlockable connecting devices make the performance of numerous ramp tests relatively onerous, because a large number of parts suffer damage after each test and must consequently be replaced.